Compositions and method for curing hydroxy hydrocarbonyl substituted siloxane resins



I thanforganic resins. l However, thesepre such as those encountered,inseawateIrja COMPOSITIONS AND METHOD FOR HY- DROXY HYDROCARBONYLSUBSTITUTED SIL- OXANE RESINS V I I John L. Speier, Pittsburgh,Pa.,jassignor to Dow Corning I Corporation, Midland, Mich a corporationof Mich- No Drawing.

Application February 14, Serial No. 488 163 12 Claims. crash-46.5

This application relates to a method of curing coinpletely condensedorganosiloxane resins.

i least the third carbon atom away, from the silicon atom,

This application is a continuation-in-part of the applicants copendingapplication Serial No. 463,062, filed October 18, 1954 (now US. PatentNo, 2,723,987, issued November 15, 1955), which in turn wasa'continuation-in-part of thethen 'copending application Serial 7 No.398,897, filed December 17, 1953.-(now abandoned,

Thisapplication is also a continuation-impart of applicants 'copendingapplication Serial No;'463,O61','filc d October 18, 1954, which isitselfa continuation-impart of application No. 398,896,:fi1ed December1' 7,' 1953',- both of which are now abandoned;

; It has long been known thatorganosiloriane rq 'make excellent hightemperature coatings for metal nd 1 I or; more i step process;

other'fsurfaces' It has alsobeen known' that these coat ings tend to bemore corrosionflresistaut; than doisimilar coatings madefrom'organicimateriala However,:the:

'organosiloxane coatings heretofore employed, especially those whichcontain only organosilicon resins, require higher temperatures andlongercuring timejthanfis needed for] most "organic finishes. In general,Iorganosilicon resins heretofore commercially "available pro ct metaland .glass surfaces from corrosion 'better' 'norganos'il'icon resinsleave mu ch to be' d' II II of protection for; metal surfacesunder I IIt w s kn w r or-tc ,app t nl hat omplet ly,

condensed organosiloxanes,;,i.e., sil'oxanes "containingno l siliconbonding hydroxyl s, co u l d be employed fgnc'oat ing base members.Howevensas is shown in 1158.? Patent 2,6 10,1 69 these materials re'qfu'I a tures'and moreprolongegl curingsc edulesth ven :j higher temperapresen't'inventio'n relates to 'a method oficurm g s l ox a cresinswhich obviates the aboveiidifliculties fItisthe object of thisinven t ion} of wr n completely o ens dtq' sufiiciently low temperaturesand 1n period of time so that thecuring will b feasible.

A t o e is lQll F in qrr s l o v resin coatings for metal: and othersurfaces I therpb jects and advantages will be apparent fror'n lthefollodescription. .s

invention relates to a of it; p I fiy g qndensed 'copolymericjsiloxanescontainingfrom 5:19 molpercgntsiloxaneunits' ofthe formula and (YOOC),R' in the'hydroxyl group is attached to at least -.the third 'carbonatom away from the silicon; R"s is a divalent or tn'- valent SQI l a YaP QI GIQ cyclo l p n hyd oca bon radical wherein each carbonyl group-isattached to at ut mayran e'fmm so cl rig-r6 25? c I II I I :general,satisfactory cures may be Qbiaillfidflnlheiiflfii g' which theQba'semembercans; I I

the sil'o'xa'ne and-, the curing compound-and thereafter I :Y is-analkylradicalor hydrogen atom and ajis an integer from l'to 2 inclusivegk isof the group monovalent hy- 'droca'rbonradicals free of aliphaticunsaturation and halogenated monovalent hydrocarbon radicals fi'ee' dfaliphatic unsaturation and n has a value from 0 to 2, the

composed of siloxane remainder of the siloxane being unitsoftl1eformulaI II I a. .ZIIISiOII- III I in "which 2' is of the group monoyalenthydro'carbon radicals and halogenated monovalent hydrocarbon radiorganiccuring'compound. in the desired proportions andl thereafter heat until asatisfactory cure isrobtained. The 1 mployed curing .ltemperatures vary.with the Jeacta t 'perature range from -'150'' C. for periods of 30minutesl -aor less. The curing operation may. be either-a one 11u .;th'mxtu wptis loxanetan a se i c rin aqmnsun mar-12 -narti lyer a edea h jpsod tt l ca i m l edi -v sdgas coat a d The method of this mventronu forzthe application of siloxane. protecuve coatings l e dipp da naaini tu aheated u nt il -the filnris cured; The proportions 'jofthe iunction lthe more a o5! idwhich X'is a functional radical of thegroup HOR Q- 7 IIwhich R is a divalent saturated aliphatic orcycloaliphaticdiydrocarbonradical in'which units in the siloran I II I If'order to'obtain s atisfactoryj'cures. The upper limitbe determined :bythe ';thermal'fstabi1ity desired in the lfinished}product. iIf a 1highdegreeof thermal stability is desired; the organofunctionalsiloxaneunits should be;

henc the stability or agent maybetemployed j l ,'{JIhEQffinctioaalorganosilicon gompound of I I same; as that-of conventional silicouefresi stability ifs 'not th' primary factor inf the' final product; i

higherramounts of the organofunctional siloxanes with a6proportionalincreasejiii the amount of organiccuring. a

- i It should be understoodgthatsiloxanes containing bath silicon bondedOH 'group's -jandsthe X groups above de- I "fined can' be curedbyrheating;them'with organofunctional curing agents. However; such aprocess does'not give'curedresins equivalent 'meth t i ve ti n;x

X n a-nyi 2 i in; hi fi x is a y i v a e igr fip srrepa di inflaccordance withflthe methods-set forth ginf the aforesaid phca io 'f fsefl sq s o l t On 9 e er ay atsdfr dicalia z re ared is r-i n to"'those preparedby'the 3 "medias applicat on fietia vNofi ed October 18,95 ne tent No- Zf 2 i 7, issued N mbe 15, 1955 (which is hereby made apart of this specifcation by reference). These siloxanes may becopolymerized with hydrocarbon substituted and/or halogenatedhydroearbon substituted siloxanes in accordance with the method setforth in said applications.

If desired the siloxanes employed herein can contain o a mo s th n onype of units. In those organofunctional siloxanes in which X is ahydroxylated radical, R can be any saturated aliphatic divalenthydrocarbon radical of at least 3 carbon atoms Such as propylene,butylene and octadecylene and any saturated cycloaliphatic divalenthydrocarbon radical of at lea t 4 a b n at s s h a and or any cyclicdivalent aliphatic hydrocarbon radical of at least 5 carbon atoms suchas cyclohexylene, cyclonentylene, m y cyclop n y ne, and

any trivalent cycloaliphatic saturated, hydrocarbon radical of at least6 carbon atoms such as g GI It should be understood that the termcarboxyl group as employed herein includes the group COOH and 4 phenyl,benzyl, tolyl, naphthyl and xenyl. R can also be any ha o enat d mq ovan hyd ca bon radical tree of aliphatic unsaturation such aschlorophenyl, dibromoxenyl, tetrafluoroethyl, pentafluorobutyl andcoma-tritluorotolyl.

For the purpose of this invention the organo-siloxanes of the formulacan be any siloxane in which Z is any monovalent hydrocarbon radicalsuch as alkyl radicals such as methyl, ethyl and octadecyl; alkenylradicals such as vinyl and allyl; ,cycloaliphatic radicals such ascyclohexyl, cyclopentyl and cyclohexenyl and aromatic hydrocarbonradicals such as phenyl, benzyl, tolyl, naphthyl and Xenyl and anyhalogenated monovalent hydrocarbon radical such as chlorophenyl,trifiuorovinyl, tetrafluorobutyl, tetrabromoxenyl anda,u,a-trifluorotolyl. The solxanes can be either homopolymers orcopolymers and there can be more than one type of Z group attached toany one silicon atom and the units can be ZSiO Z SiO and Z SiO togetherwith limited amounts of SiO- units.

The relative proportions of the siloxanes and the poly- ;functionalorganic curing compounds are not critical. Obviously, however, the mosteflicient operation will be .obtainedwhen the organic curing agent isemployed in 7 units (i.e., as in Example' 2).

COOY in which Y is an alkyl radical such as methyl,

ethyl or octadecyl.

In the organofunctional siloxane units R can be any monovalenthydrocarbon radicalfree' of aliphatic unsaturation such as alkylradicals such as methyl, ethyl and octade'cyl; cycloalkyl radicalssuchns cyclohexyl and eyclopenty'l and ar'omatie hydrQQatbQH iadicals as15 droxyl reactive polyfunctional organic compound can be employed suchas dicarboxylic acids such as maleic, phthalic, terephthalic, malonicand sebacic acids and their esters, or anhy drides anddiisocyanates suchas m-tolhene diisocyanate, p,p'-diisocyanato-diphenylmethane andparadiisocyanato-benzene. The'isocyanates are the preferred curingmaterials for the hydroxylated siloxanes. Inthose cases where X is anacid or ester group any polyfunctionalorganic compound'which is reactivetowards carboxylic ac'ids jor their esters canbe employed. Specificexamples of such compounds are polyhydric alcohols such as ethyleneglycol, glycerine, ,pentaerythritol and'poly: amines such as ethylenediamine, octamethylene triamin'e, hexamethylene'diamine and octadecylenediamine. The diamines'are the preferred curing materials for .thecarboxylated siloxanes; t v

The superior qualities of the coatings formed by the method of thisinvention is specifically exemplified in their superior resistance toattack by chemical reagents. This is shown by the fact that metalsurfaces which are coated show much less corrosion when'exposed to saltyatea caustic and acid than resins prepared frong a ivmidnalorganosiloxanes. The 'method' of this invention is equally applicablefor the preparation of si loxane molding compositions, laminates andcast articles.

, The following examples'are illustrative only and should not beconstrued as limiting the invention which is proper- 1y delineated intheappended claims.

' EXAM L mol percen of the above siloxa ne i we'recohydroly zed in thepresence of toluene and ether. The resulting resin was then refluxed ina mixture of 100 ml. toluene, 50 inl. ethanol and g. of potassiumhydroxide for 3 hours at8l C. The resulting product was a siloxanecopolymer resin composed of 55 mol percent phenylmethylsiloxane, molpercent monophenylsiloxane, 15 mol percent monomethylsiloxane and 15 mol'A,70% toluene solution of this resin was mixed with an equivalentamount of'm-toluenediisocyanate. Sheet. iron panels were coated withthissolution and cured 30 "percent samba minutes at 120i C.}' The'films'obtained were light in 7 color, glossy and "flexible and wereunaffected by hydro gen chloride and by saturated sodium chloridesolution when heated-in the latter 3 hours at 95? C.

Equivalent results were obtained, when the resin was reacted withp,p'-diisocyanato-diphenylmethane..j"

' EXAMPLE 2 '97 of phenylmethyldichlorosilane; 20.8 g. of methyl- Vtrichlorosilane and 29.4 g. of phenyltrichlorosilang? 19 v 9 h yld ew ieas were dissolved in 25(l arrowhead-1154-ofan ethylether and hydrolyzedwith water; During hydrolysis the mixture was cooled in anicebath andmade almost neutralwith sodium hydroxide Thc organicflayer was weight of,the resin s'olid's'. The resulting lso liitiorilwa's "free ofsilicon-bonded "hydroxyl's' and wa'ls neutralized; I washed and dried.The solution was concentrated'to by weight solids. Theresulting'siloxane'wasthe copoly-' merhaving the composition 50.8 molpercent phenylmeth- Hylsiloxane, 13.9 mol percent monomethylsiloxane,13.9

t monophenylsiloxane, 7.5 mol percent diphcny i n and -9 mo P rc nt. 1

E uivalent tutorin Meooo I l Equivalent. resultswereobtainedwhendiethylen 7 V percent dirnethyl siloxane, 110. mol percent 'chlorophenyl -washed until neutral, stripped of ether'and azeotropically Vfdried. It was then completely condensed by refluxing in a-25% toluenesolution for 6 hours with'potassium hydroxide in amount of ;,2% byweigh-tv basedjon'thepercent monophenyl siloxane'aridi65:,mol,p ce

i a y 5 i; heated with hexamethylene diamine inaccordancewithi i theprocedure of Example 2 a cured siloxane'iresin is atmosphere- Theresulting-Viscous resin was'dissolved in 7 Panels of sheet iron werevdipjcoat'edflwith autoluene solution of resin (A). and were Compared,with a commercial phenylmethylpolysiloxane resin' (B) having thecomposition 50.8 mol pe'rcent phenylmethylsiloxane,

27.8 mol percent monomethylsiloxane, 13.9 mol percent monophenylsiloxaneand 7.5mm percent diphenylsiloxane which contained about 1.5%siliconbondedQ I-I groups and a small amount of a zinc naphthenatecatalyst. 'The panels were cured as shown in the table below and wereimmersed in a saturated aqueous sodium chloride solut1on at -95" C. andtheeffect on the filmi'was noted as shown in the table. Plate glass wascoated witliresin's (A) and (B) and the resulting panels cured .as shownv 1n the table below and then immersed in concentrated aqueous NaOH andtoluene at 30 C. 'forpthe times shown. v

. Table I Immersion Media Resin Curing Schedule Results AAirdried15min.- ul n anecteamizrs. Saturated aqueous C. for 15 mln NaOl.250 C.Ior15min- B IdentlcaL; Film blistred and broke in 4111's. 7 V A IAir.dried15min---;. ui ancetedinaj a a s-- Concentrated 150-O.for 1-5mln.'..---

aqueous NaOH 25050. forl hour r B Identical Fflm softened J 1'andloosened- I 1 in'2days..-- 1 V A Identlcal.-...'... sonsnedinlifiTo1uene.. .I'

H 1 B Identical...

- l *EXA PLE'3 amine is employed in the procedure of Example}.

" EXAMPLE-.44.

When a completely'oondensed copolymer having composition 5 mol percent.viny1phenylsil9xane,.- 501 1101 diisocyanate in accordancewith theplrocedure oi li xams T pie 1, satisfactory. as: the siloxane resin? isobtam EXAMPLE 5 aeompletely sham manyobtained. a a

p EXAMPLE 6 y Whenj a completely condensed 'copolymeric endgame ofthe-formula 50 mol percent phenylmethylsi1oxane,'35

"mol percent monophe'nylsiloxane and 15 mol percent,

phenyl-gamma-hydroxypropylsiloxane; is reacted with Vrn-toluenediisocyanatein.accordancevwiththe procedure t vl i 5 ofExample 1, a fd Siloxane isi obtained.. was mixed aim- 13 ;1.015101 ofhexameth ylene di amine and heated at'25 0- (3.. for 2 hours inanitrogen EXAMPLE 7 '4 When a completely condensed copolymer of 50 mol,phenylmethylsiloxa'nc, 25 ,mol percent u,a,u-tri- 1 f P c ntfluorotolylsiloxane. and 25 mol percent is hexamethylene the a amoa thatthere is one amino group per one carboxyl group in the mixture andthereafter heated at 150" C. for 30 in-which X is a functional radicalof the formula HOR'- in which R is a radical of at least three carbonatoms and is of the group consisting of divalent saturated aliphatic anddivalent saturated cycloaliphatic hydrocarbon radicals in all of whichthe hydroxyl group is attached to at least the third carbon-atom awayfrom the silicon, R is of the group consisting of monovalent hydrocarbonradicals free of aliphatic unsaturation and halogenated monovalenthydrocarbon radicals free of aliphatic unsaturation and n has an averagevalue from to l inelusive, the remainder of said siloxane being composedof siloxane units of the formula in which Z is of the group consistingof monovalent hydrocarbon radicalsand halogenated monovalent hydrocarbonradicals and m has an average value from 0 to 3 inclusive, saidcopolymeric organosiloxanehaving an average of from 1 to 1.7 inclusivetotal organic groups per silicon atom and (2) a polyfunctional organiccuring compound selected from the group consisting of diisocya'nates,hydrocarbon dicarboxylic acids, and esters and .anhydrides of saidacids, until the siloxane is cured.

2. A method of curing an organosiloxane which comprises heating amixture of (1) a completely condensed copolymeric siloxane containingfrom to 75 mol percent siloxane units of the formula (HOR)R,;SiO

in which R is a radical of at least three carbon atoms and is selectedfrom the group consisting of divalent sat- =urated aliphatic anddivalent saturated cycloaliphatic hydrocarbon radicals in all of whichthe hydrexyl group is attached to at least the third carbon atom awayfrom the silicon, R is of the group consisting of 'monovalenthydrocarbon radicals free of aliphatic unsaturation and halogenatedmonovalent hydrocarbon radicals free of aliphatic unsaturation and n hasan average value from 0 to l inclusive, the remainder of said. siloxanebeing composed of siloxane units of the formula Z,,,SiO V T in which Zis of the group consisting of .monovalent hydrocarbon radicals andhalogenated monovalent hydrocarbon radicals and m hasan average valuefrom 0 to 3 inclusive, in said copolymeric siloxane there being anaverage of from 1 to 1.7 inclusive total organic groups per silicon atomand (2) a diisocyanate, until the siloxane is cured. s

3. A method of curing a siloxane which comprises heating a mixture of(l) a completely condensed copolymeric siloxane containing from 5 to75mol percent of from 1 to 1.7 inclusive total organic groups per siliconatom and (2) a diisocyanate, until the siloxane is cured. 1' 4. Amethodcomprising heating a mixture of a s completely. condensed copolymericsiloxane containing from 5 to mol percentgannna-hydroxypropylmethylsiloxane, the remainder of said siloxane beingmethyl and phenyl siloxane units, said siloxane having on the averagefrom 1 to 1.7 inclusive total organic groups per silicon atom and (2) adiisocyanate, until the siloxane is cured.

5. A method comprising heating a mixture of 1) a completely condensedcopolymeric siloxane containing from 5 to 75 mol percent of polymericunits of the general formula where x is an integer of from 0 to 1inclusive, the remainder of said copolymeric siloxane being siloxaneunits of the formula Z SiO T in which Z is selected from the groupconsisting of monovalent hydrocarbon radicals and halogenated monovalenthydrocarbon radicals and m is an integer of from 0 to 3 inclusive, saidcopolymeric siloxane having an average of from 1 to 1.7 inclusive totalorganic groups per silicon atom and (2) a diisocyanate, until thesiloxane is cured.

6. A method comprising heating a mixture of (1) a completely condensedcopolymeric siloxane containing from 5 to 75 mol percent of siloxaneunits of the formula HOCH CH CH (CH ),,SiO

where x is an integer of from Um I inclusiv'e,-the remainder of saidsiloxane being methyl and phenyl substituted siloxane units, said.siloxane having on the average from 1 to 1.7 inclusive total organicgroups per silicon atom and (2) a diisocyanate, until the siloxane iscured.

7. A resinous coating composition in which the resin forming constituentconsists essentially of a mixture of (l) a completely condensedcopolymeric siloxane containing from 5 to 75 mol percent ofpolymericunits of the general formula I HOCH CH CH (CH ),SiO

where 'x "is an integer of from 0 to 1 inclusive, the re mainder of saidsiloxane being siloxane units of the. formula V i 7 Z,,,Si0,,

in which Z is selected from the group consisting of mono valenthydrocarbon radicals and halogenated monovalent hydrocarbon radicals andm is an integer of from 0 to 3 inclusive, said copolymeric siloxanehaving an average of from 1.to'1.7 inclusive total organic groups persilicon atom and (2) a diisocyanate, the diisocyanate being present inan amount such that there is from one of the isocyanate groups for everyhydroxypropyl group in the siloxane to one mol of the diisocyanate 'permol of the hydroxypropyl substituted siloxane units present.

8. A resinous coating composition in which the resin forming constituentconsists essentially of a mixture of (1) a completely condensedcopolymeric siloxane con taining from 5 to 75 mol percent siloxane unitsof the formula r and is selected from the group consisting of divalentthe siliconJR is of the group consistingofimonovalent posed of siloxaneunits of the formula in which Z is of the group consisting of monovalenthydrocarbon radicals and halogenated monovalenthydrocarbon radicals andm has an 'averagevalue from' 0 to 3 inclusive, in said copolymericsiloxane there :being an average of from 1 to 1.7 inclusive totalorganic groups per silicon atom and (2) a polyfunctional, organiccurfjhydrocarbon radicals free o't aliphatic unsaturationfa'nd fhalogenated monovalent hydrocarbon ra'dicalsfree of ali-' 1 'phaticunsaturation and n has an average value from 0 to 1 inclusive, theremainder of said siloXane being comawhich Z1is o fthe groupconsistingof monovalenthydrocarbon radicals and halogenated monovalent hydrocarbonradicals and m'has an average value from O to 3 ining compound selectedfrom the group consisting of'diisocyanates, hydrocarbondicarboxylicacids, and esters.

and anhydrides of said acids. 7

9. A resinous coating composition in which the resin forming constituentconsists essentially of a mixture of (l) a, completely condensedcopolymeric siloxane containing from 5 to 75 mol percent siloxane unitsof the, a

in which R is a radical of at least threecarbon atoms and is selectedfrom the group consisting of divalent saturated aliphatic and divalentsaturated cycloaliphatic hydrocarbon radicals in all of whichthehydroxyl group is attached to at least the third carbon atom away fromthe silicon, R is of the group consisting of monovalent hydrocarbonradicals freeof aliphatic unsaturation and -halogenated monovalent"hydrocarbon radicals free of aliphatic unsaturation and n .has anaveragevalue from '0 v to, 1 inclusive, the remainder of said siloxane beingcom- I r posed of siloxane unitsof'the formula per siliconatorn, and 2)adiisocyanate. V

1 10. A'resinous coating composition in (1) a completely condensedcopolymeric siloxane con taining from 5 to 75 mol formula in which R' isa divalent saturated aliphatic radical at least three carbon atoms inwhich the hydroxyl groupis attached to the terminal carbon atom, R is ofthe group consisting of monovalentjhydrocarbonradicals free of clusive,in 'saidcopolymeric siloxane there being an average of from 1 to 1.7inclusive total organic groups per silicon atom, and (2) a diisocyanate.

11 1; A method of curing an organosiloxane which com prises heating amixture of ('1) a ,completely'condensed copolymeric siloxane containingfrom 5m 75 mol percent siloxane units of the formula I y (HOR)R,,SiO

in which Ris a saturated aliphatic hydrocarbon radical of at 'leastthree-carbon atoms in which the hydroxyl group is attached to theterminal carbon atom, R is selected from the group consisting-ofmonovalent hydrocarbon radicals free of aliphatic unsaturation andhalogenated monovalent hydrocarbon radicals tree of aliphaticunsaturation and n has an average value fromO to '1 inclusive, theremainder of said'siloxane being composed of siloxane units ot'theformula Z ,SiOF

' 2 V in which Z is of the group consisting of monovalent hydrocarbonradicals and halogenated monovalent hydrocarbon radicals and m has anaverage value from 0 60 percent siloxane 'oi the to 3 inclusive,insaidcopolymeric siloxane therebeing an 7 average of from 1 to 1,7inclusive total organic groups per silicon atom, and (2) -a-polyfunctional piganic curing compound selected-fromFthe ,1 group jconsisting of cyanates, hydrocarbon dicarboxylic acids, andesters andanhydrides ofsaid acids, un'tilf the siloxane is cured. I 12. A resinous'coatingcompositionin which the "resin f.- V I p o 0 n J formin'g' -c0nstituentconsistsessentiallymf a of." I in which Z is of'thegroupconsisting'of monovalent 'hy I, I? (1)73 completelycondensed-gopolymenc drocarbon radicals and halogenatedmonovalenthydrocarbon radicals andQm has an average value from 0 to 3 Y inclusive,in'said-"cppo1ymeric- .siloxane there being'an" ,7 average of from 1' to1.7 inclusive total organic groups mol percent P hich the tormm gconstituent consistsessentiaHy sp e; ma eflsaldvsfloxane ms' methyl ndphe'tiyl siloxane units, said siloxane having an average of 'atomf and(2) a diisocyanate, f, .5 lieferences Cited i the meet this patent I vUNITED STATES PATENTS 2,443,898 Ellingboe June 22, 1948 2,550,205 SpeierApr. 24, 1951 2,687,418 Sommer Aug. 24, 1954 2,768,193 Gilbert Oct. 23,1956 ,from lto 1.7 inclusive total organic groups per V

8. A RESINOUS COATING COMPOSITION IN WHICH THE RESIN FORMING CONSTITUENTCONSISTS ESSENTIALLY OF A MIXTURE OF (1) A COMPLETELY CONDENSEDCOPOLYMERIC SILOXANE CONCONTAINING FROM 5 TO 75 MOL PERCENT SILOXANEUNITS OF THE FORMULA